Fix test_http:HTTPTests.test_no_content_length

Fixes Travis CI build failing under nightly 3.6-dev:
- http.client.HTTPConnection now has _get_content_length static method
  instead of _set_content_length. Mocked both regardless of Python
  runtime version
- Added 3.6 env to tox config

1 files changed, 6 insertions, 4 deletions

diff --git a/cherrypy/test/test_http.py b/cherrypy/test/test_http.py
index f918ebc9..48b60811 100644
--- a/cherrypy/test/test_http.py
+++ b/cherrypy/test/test_http.py
@@ -115,11 +115,13 @@ class HTTPTests(helper.CPWebCase):
             c = HTTPSConnection('%s:%s' % (self.interface(), self.PORT))
         else:
             c = HTTPConnection('%s:%s' % (self.interface(), self.PORT))
-        if hasattr(c, '_set_content_length'): # python 2.6 doesn't have it
-            with patch.object(c, '_set_content_length'):
+
+        # `_get_content_length` is needed for Python 3.6+
+        with patch.object(c, '_get_content_length', lambda body, method: None, create=True):
+            # `_set_content_length` is needed for Python 2.7-3.5
+            with patch.object(c, '_set_content_length', create=True):
                 c.request("POST", "/")
-        else:
-            c.request("POST", "/")
+
         response = c.getresponse()
         self.body = response.fp.read()
         self.status = str(response.status)